Q: So I understand the math, 3500 calories equals one pound. But there are obviously other factors, right? Otherwise my husband who eats cookies, chips, and drinks tons of Mountain Dew all day would gain tons of weight — yet he barely weighs 160 lbs. (and pretty much has weighed that his whole life). I mean he is pretty active, but so am I, but if I were to eat half as much as him I would gain at least a pound! What's the deal? — Keri

A: Ah Keri. This is such an awesome question regarding the unfairness of Mother Nature. To best explain this, we turned to Michele Olson, PhD, professor of physical education and exercise science at Auburn University Montgomery, for a more detailed, scientific answer.

"You are correct. One pound of fat is rich with a lot of energy — 3,500 calories to be exact. And, if we did some math on the dietary values of what your husband consumes, those values would be high, and, in a lot of cases, should indicate fat and weight gain. But, the old idea that some people have a faster metabolic rate is not a bit of physiological folklore. It's true and does explain how your husband can ingest a lot of calories (even "bad" ones) and not gain weight," explains Olson.

Find out why men lose weight easier than women after the break!

Yes, men do get to eat more and (generally) weigh less.

The unfair news? Men have much more active metabolic mass on their bodies, says Olson. They have more skeletal muscle, bigger hearts, bigger kidneys, and less body fat proportionately for their total body weight. Each pound of muscle burns six calories. The heart and kidneys are heavy consumers each needing at least 100 calories per day. And, fat only burns two calories per pound, Olson says. (Sigh, thanks Mother Nature — as if bearing children wasn't enough, we have to carry the extra body fat, too).

And yes, most men have more muscle and higher metabolisms than women.

"This is a case where the other person can eat more due to having a higher metabolic rate. In fact, his body might actually need those extra calories to supply his larger, muscle-based organs. Lance Armstrong, for example, is a lean machine and does not weigh much for his height. But, his heart is huge! Not only does he get to eat a lot of calories due to training, he must eat enough to sustain what's not seen on the outside (his large heart) in conjunction with his low-fat, primarily muscled (though not huge) physique," explains Olson.

The bottom line Keri? There are many reasons to enjoy being a girl, but missing out on a naturally high metabolism isn't always one of them (although there are always exceptions)! We like to think of it as nature's way of keeping the species healthy. It's our job to push the nutritious stuff, so your family isn't eating junk food all the time, right?

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